Even if the project is not up and running by March 31, responsibility for introducing fluoridation in parts of Southampton, Eastleigh, Totton, Netley and Rownhams will fall to the new body Public Health England.

Councils will have the power to reverse the scheme, but they are likely to have to stage expensive public consultations before making any move.

Despite the authority having previously voted to oppose the plans, Southampton City Council leader Richard Williams admitted there is no money in the cash-strapped council’s budget to fight the scheme.

Health chiefs insist fluoridation is the best way of improving dental health in Southampton, particularly among children in more deprived areas.

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The SHA’s board unanimously approved the scheme in February 2009 despite 72 per cent of the 10,000 respondents who participated in the public consultation saying they opposed the plans, with fears over a lack of democracy and possible side effects.

Health bosses said they were convinced by arguments fluoride will help cut high rates of tooth decay, particularly in under-fives.

At the time the plan was introduced Southampton was said to have had an especially poor record on rates of rotten teeth in children, and although later surveys suggest the situation has improved the SHA has said it remains confident its decision was right.

But although it is working with Southern Water on how best to implement the scheme, bosses admitted they still don’t yet know how much it will cost, or the exact area it will cover.

This weekend’s public meeting is being held at the Gurdwara Nanaksar, in Peterborough Road, Bevois Valley, at 6.30pm on Saturday, with representatives from many of the city’s religious organisations attending to combat the plans.